Blaise Prod'hom

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We studied the pH dependence of the proton-induced current fluctuations that appear in single open L-type Ca channels when monovalent ions are the charge carriers. We used different methods of analysis to obtain kinetic measurements even under conditions where the individual transitions were too fast to be resolved directly as discrete current steps between(More)
We further investigated the rapid fluctuations between two different conductance levels promoted by protons when monovalent ions carry current through single L-type Ca channels. We tested for voltage dependence of the proton-induced current fluctuations and for accessibility of the protonation site from both sides of the membrane patch. The results strongly(More)
A Ca(2+)-blockable monovalent cation channel is present in the apical membrane of the ectoderm of the gastrulating chick embryo. We used the patch clamp technique to study several single-channel permeation properties of this channel. In symmetrical conditions without Ca2+, the Na+ current carried by the channel rectifies inwardly. The channel has an(More)
We have investigated the effects of two oppositely acting enantiomers of the 1,4-dihydropyridine derivative 202-791 on voltage-dependent Ca channels by combining electrophysiological techniques and binding studies. The (S)-enantiomer of 202-791 promoting prolonged openings of single Ca channels, and thereby increasing transmembrane Ba currents, was(More)
The mechanism by which ions deliver their message to effector proteins involves a change in the protein conformation which is induced by the specific interaction of the ion with its binding site on the protein. In the case of an ion-channel protein, conformational changes induced by permeant ions and the consequences for channel function have received(More)
The structural and thermodynamic factors responsible for the singly and doubly occupied saturation states of the gramicidin channel are investigated with molecular dynamics simulations and free energy perturbation methods. The relative free energy of binding of all of the five common cations Li+, Na+, K+, Rb+, and Cs+ is calculated in the singly and doubly(More)
A rapid, transient rise in the free cytosolic Ca2+ concentration ([Ca2+]i) is one of the earliest events in neutrophil activation and is assumed to be involved in many of the subsequent cellular reactions. Both Ca2+ release from intracellular stores and Ca2+ influx from the extracellular space contribute to the rise in [Ca2+]i. In an attempt to assess the(More)
In the chick embryo (20 h incubation, gastrula stage), the apical membrane of the ectodermal cells shows a high density of a non-selective cation channel which is blocked by very low extracellular Ca2+ concentrations. Properties of this channel were studied at the single-channel level using the patch-clamp technique in the cell-attached mode. With 1 mmol/l(More)
Voltage-dependent calcium channels are widely distributed in excitable membranes and are involved in the regulation of many cellular functions. These channels can be modulated by neurotransmitters and drugs. There is one particular type of calcium channel in cardiac cells (L-type) whose gating is affected in different ways by beta-adrenoceptor and(More)